. >> reporter: again, tamron, the white house announcing that president obama and the first lady will head to a memorial service on thursday for those killed in the explosion. this town is still shaken and the president once again taking on the role of comforter in chief. >> thank you, gabe. right now, flooding from heavy rains is causing havoc in at least six midwestern states. this could be just the beginning. at least three people have died and floodwaters caused the rescues, force evacuations and close roads and bridges. near st. louis, more than 100 barges broke free in the rain swollen mississippi, disrupting river traffic. a frantic sandbagging effort is underway in some places as the mississippi and other rivers keep rising. this is all the result of fast -- last week's torrential storms which dumped a month's worth of rain in a matter of hours. meantime, more rain is expected. the weather channel meteorologist kelly cass joins us with the latest. what can you tell us? >> not just a heavy rain but the snow melt that is adding to the rivers rising. we're still having major floo